>> Friday, January 07, 2011

Some thoughts on the early week storm system. Below are two maps outlining my general thoughts on precip type areas. Keep in mind these boundaries are not hard and fast and might be adjusted. Also keep in mind I actually drew them up this morning. After reviewing the 12z data, I might tweak a spot or two, but the overall ideas remain the same.

This is seemingly always the range leading up to winter weather systems where lots of uncertainty seems to develop. I know seeing the QPF numbers continue to gradually wane, especially in NC, is extremely painful for snow fans to watch. I feel your pain. Generally speaking, there has been a trend in the modeling of weakening our southern branch feature every so slightly quicker than some of the previous runs.

Here is something of note....our disturbance is just as strong on the most recent run as it enters the Lower Mississippi Valley that it was on its run 24 hours ago. The quicker weakening takes place as it heads for the upper Southeast. I really think it is just a subtle difference in some energy over the New England states, but equally if not more important is the latest Euro is a little stronger with the next piece of energy in the Rockies.

Just comparing the Euro to the 12z run 24 hours ago, the difference in strength of the system as it enters the Southeast is small, but it is enough to cut the QPF numbers.

This is why I have been stressing, and continue to stress now, to not get wrapped up in QPF numbers. It is not good to get really excited or really down at this point about QPF, even still at this point.

Listen....the southern branch feature will definitely weaken as it approaches the Carolinas. It is a matter of how quickly it will weaken. That is the big question mark for Carolinas precip amounts.

Are the lower precip totals going to be a reality? Possibly, but possibly not. It is simply too soon to know.

This is really the point where I will just keep the forecast ship steady and true as we head into the weekend. I will not change the wording from my overall ideas that I have had out there. The potential for a widespread, significant winter storm from the Lower Mississippi Valley into the Carolinas is still very much there.

Will there be some disappointed people. Yes? Will there be some very happy snow fans? Yes.

Let's give it another 36 hours or so before anybody in the region (from Lower MS Valley to Carolinas) starts cliff-diving or starts the celebrations.

Thanks Matt. From what I understand, synoptically, there should be higher amounts of precipitation under the good vorticity in the carolinas but the models are not showing that. Would you agree with that assessment? Is that a common problem with models overall? Thanks.

Hey guys....I appreciate the questions, but I really don't ever put our accumulation prediction until within 48 hours of an event. Lots could still change with precip amounts.

Yes, in time, that snow to wintry mix line will lift north....but that is a very small scale thing and impossible to resolve this far in advance.

Brad, the models were doing some odd looking stuff with the northern edge of the precip shield. Synoptically, yes, you would expect it to be farther north than some of the earlier runs had. 18z GFS seems to be correcting in that direction.

I'm in Danville, VA right now and there is 2" of snow on the ground. Funny thing is that 1 mile down the road there is only a dusting...if you can call it that. I've never seen that much of a difference in such a small area. I could watch it get deeper the further north I drove, which like I said is literally one mile distance.